Process of working refractory metals.



UNITED sTAirnsrgr-E T OFFICE.

amncnrno vex Pianist, or wrnmnnsnonr, NEAR BERLIN, axn nnnmanx POI-IL, or cnanro'rrsxsuno, GERMANY, assrexoas r0 GENERAL ELECTRIG COMPANY, A

CORPORATION OF NEW YORK.

PROCESS OF WORKING REFRACTORY METALS.

No Drawing.

Specification of Letters Patent.

To all whom, z'tmay concern:

Be it known that we, MARCELLO VON PI- RANI, a subject of the King of Italy, residing at Wilmersdorf, near Berlin, Germany, and HERMANN Form, a subject or the German Emperor, residing at Charlottenburg, near Berlin, Germany, have invented certain new and useful Improvements in Processes of Working Refractory Metals, of which the following is a specification.

The present invention relates to the working of refractory metals or alloys thereof by the aid of auxiliary material with which the refractory metal is incorporated to form a composition or mass which can be readily worked, the auxiliary material being ultimately eliminated: this mode of working such metals and of manufacturing various articles from them is, in particular, practised in the so-called auxiliary metal process, according to which a certain quantity of another metal may be added to refractory metal which in itself has little initial ductility with the result of increasing its ductilit-yso that it can be easily worked and such other metal subsequently wholly or partially driven out by heating. In the process as heretofore practised and as described for instance in Patent No. 927,935 issued to Von Bolton July 13, 1909, the mixture of'the two metals was worked into the form of a filament by rolling or drawing and then after the filament had been formed is gradually expelled during the mechanical working so that by the time the material is brought to filamentary form, all or nearly.

all the auxiliary metal has been expelled.

By the method which forms the subject of the present invention,and which is for sake of clearness hereinafter described in detail as applied in connection with the auxiliary metal process rthe working of the composition or mass is in itself greatly facilitated, and in the case of tungsten, at least, may be made to yield a body consisting wholly of refractory metal and having properties of ductility and the like usually absent from refractory metal bodies produced by the auxiliary metal process or in similar ways. Other advantages may also be. attained.

According to the invention, the working I easily be avoided.

of the material (as by rolling or drawing) ,indifl erent or reducing atmosphere, as, for

example,'in a hydrogen atmosphere. For this purpose, the die or rollers may after insertion of the body to be rolled or drawn be mclosed in a glass receptacle through whlch a stream of hydrogen is passed. The material to be worked (wire to be drawn into filaments for incandescent lamps, for example) is brought to a high temperature by electric current,as to bright red heat,

.or even higher yet, to incipient white heat.

One advantage of thus drawing the wire at high temperature is that the drawing can be carried out with very much greater rapidity and all danger of breakingthe filament can The diamond dies are also less worn, and in the drawing down of a wire in successive steps the gradations or steps can usually be made considerably larger. Moreover by regulation of the temperature and duration of the'heating of each section of the conductive-Wire as it is being drawn the process can be controlled in such a manner that during such drawing the wire is heated tosuch a degree that a part of the auxiliary metal is expelled. In spite of this gradual diminution of the content of auxiliary metal the drawing process can be many times repeated and the reduction of the cross-section of the wire thereby carried very far, since, on the one hand, the drawing is in itself greatly facilitated by the high temperature, and since, on the other hand, by the conjunctionwof the elimination 'of auxiliary metal and the simultaneous compressive mechanical working the growing brittle of the wire which otherwise occurs during the expulsion of the auxiliary metal is in large measure prevented. In some cases metal wire can be obtained which contains only the smallest amount of auxiliary metal and which nevertheless possesses very considerable ductility. Indeed, in the case of tungsten, perfectly pure refractory metal of high ductility can finally be obtained by this progressive compressive working of the material during expulsion of the auxiliary metal.

In practice the expulsion of the auxiliary metal in this process takes place mainly in the portion of the wire which is about to Patented Aug. 26,1913. Applicat'iomfiled November 2, 1911. Serial No. 658,160.

mechanical strength may not be too much diminished. Of course; the procedure may instead be so conducted that the removal of,

the auxiliary metal is performed between each two steps in the working of the material as a special distinct operation.

The present method is particularly suitable for the treatment of tungsten metal with a small amount of nickel as auxiliary metal. These compositions of tungsten with nickel are of themselves very ductile and possess very high extensibility, and besides allow the employment of very high temperatures. It is accordingly possible in dealing with nickel and tungsten to work with especial rapidity and safety, and the final products are very uniform. v By the employment of hydrogen, in particular, the coating of oxid which sometimes forms is avoided, so that the drawn wire has a very pure surface with a strong metallic luster and needs no cleaning. In addition the dies are saved in consequence of the absence of the thin coating of oxid.

WVhat we claim as new and desire to secure by Letters Patent of the United States, is,

1. In the working of tungsten incorporated with auxiliary material to form a workable mass, the-method of securing ductile bodies consisting of tungsten alone which consists in working the mass and gradually eliminating the auxiliary material as the working progresses until the mass is entirely freed from it.

2. The method of carrying on the process of working refractory metals incorporated with auxiliary metal which consists in working the composition comprising the refractory metal and the auxiliary metal while hot, and gradually eliminating the auxiliary metal as the working progresses. v

3. The method of carrying on the process of working refractory metal incorporated with auxiliary metal into fine wire which consists in working down the size of the wire by successive steps, and removing a portion of the auxiliary metal during each step.

4. The method of carrying on the process of working tungsten incorporated with nickel which consists in drawing the composition comprising tungsten and nickel through a succession of dies, the material being heated as it enters each die sufiiciently to expel a portion of the nickel.

In witness whereof, we have hereunto set our hands this 14th day of October, 1911.

' MARGELLO VON PIRANI.

HERMAN N POHL.

Witnesses:

HENRY HASPER, WOLDEMAR HAUPT. 

